The Times of London calls this "probably the best modern house in the world." Designed by Danish architect Jorn Utzon, the mastermind of the Sydney Opera House, for his colleague Povl Ahm, the house is on the market for the first time since it was built in 1962—for £2.5 million. Constructed of pale-yellow London brick, rough and polished concrete, timber ceilings and fittings, teak windows, and white Swedish Hoganas floor tiles, it stands out among the "half-timbered horrors" of the Hertfordshire suburbs. See more photos at The Modern House.